Heretofore, others have provided elevators for bulk materials which employ a pair of engaging belts which hold the material therebetween as it is elevated from one level to another. One such belt elevator is shown in U.S. Pat. No. 3,805,946 issued Apr. 23, 1974 to Earl W. Yateman, Anthony D. Janitsch and Warren R. Vaughan on a conveyor apparatus. In this prior belt elevator, each set of troughing rolls, includes a central roller and a pair of slanting side rolls whose axes diverge toward the central roller. As the diverging edges of the troughed belt come into engagement with the edges of the cooperating belt, they are angularly disposed in relation to edges of the cooperating belt. This tends to permit bulk material to move into the space between the edges prior to the edges being brought into sealing engagement in the elevating portion of the belt elevator, thus interferring with proper sealing of the belt edges. Also heretofore, it has been suggested that the elevating portion of a belt elevator includes substantially vertically disposed engaging belts. In copending U.S. Pat. application Ser. No. 564,434, filed Apr. 2, 1975, a belt elevator is shown wherein the vertically disposed belt portions in the elevating zone are urged toward one another by fluid pressure. In copending U.S. Pat. application Ser. No. 564,431, filed Apr. 2, 1975, the confronting portions of the belts in the elevating zone of a belt elevator are disposed within a pressurized fluid plenum and opposed edge rollers are additionally provided to assist in holding the belt edges in sealing engagement. In order to efficiently elevate a required volume of known bulk material by a vertical belt elevator, it has been found desirable to use upper and lower transition zones above and below the vertical elevating zone, the upper and lower transition zones including rollers defining a curved path which changes the direction of the belts from horizontal to vertical and from vertical to horizontal. It has also been found desirable in such an elevator to employ staggered edge rollers in the elevating zone of the type disclosed and claimed in copending U.S. Pat. application Ser. No. 564,432, filed Apr. 2, 1975, so as to more effectively seal the belt edges. However, the prior art troughing roller arrangement for the transition zones permitted some bulk material to be captured between the belt edges and this material would tend to remain between the edges as they pass between the opposed staggered edge rollers in the elevation zone. If the bulk material trapped between the confronting belt edges is significantly large, the sealing relationship between the belts may be ineffective and material may escape.